On my last trip I used trail-running shoes in Lapland, which is an absolute no-go for most standard hikers. As this trip was to try out ultralight hiking strategies under more severe conditions, I just had to try it out. I used a pair of mesh trail runners which were in no way water resistant and had a good sole with some kind of spikes. They were perfectly well sprung, so I walked in them as on clouds.
My prediction was: Wet shoes all the time.
I was right, and fine !
I had rain, wind, temperatures between 4 and 10 °C, rivers to walk through and a lot of mud and swamp(knee deep). I always had warm feet, had absolutely no problem with blisters or cracked skin from the complete wetness. I didn’t have to change my shoes the whole day. In the evening I changed the socks, used some fat creme and put on dry socks. This brought me fine through the whole trip. It was especially nice in the morning to put on the wet shoes. In boots I always had cold feet for the first half our, in the mesh shoes my feet were warm in about a minute. From my point of view all the common prejudices are nonsense.
But there are definite downsides of this hiking technique (which were not mentioned by anyone):
Mud accumulates in the shoe. After 3 days I recognized that in my socks and between the socks and the insole a lot of mud accumulated(~2mm in the sock,~4mm on the insole). This led to an uneven ground under my feet and to a possible spot to build up blisters. Therefore I had to clean the socks every evening and the insole and shoe itself(under the insole) every second day.
They don’t dry. The often mentioned sentence that boots don’t dry on the trail but mesh shoes do might be true for warm Californian PCT sections but not for northern-European hiking conditions. As every other piece of gear, it will stay wet. Doesn’t matter how long you walk in the dry.
They grow stiff. The continues partly dry, wet and mud conditions made the shoes stiff, you had to batter them to make them soft again. This might be a special issue of my pair of shoes…
Socks wear out a lot faster. During this trip I completely destroyed the SmartWool socks I used.